Kommentar zu Dewarim 4:26

העידתי בכם I CALL AS WITNESSES AGAINST YOU [THE HEAVENS AND THE EARTH] — Behold I summon them to be witnesses that I have warned you.

את השמים ואת הארץ, as spelled out in 11,17 where it is described that these “witnesses” would withhold the harvests the people depend on if they failed to observe the laws of the Torah.

העידותי בכם היום “I call up against you as witness this day!” that you will perish in short order, (if you ignore my warnings) for He will not have a great deal of patience with you once you have become guilty of idolatry. Even though this paragraph is in the nature of a warning, Moses did not phrase it as if it were something conditional, i.e. he did not preface it with the word “אם, etc.” The reason is that over and above being a warning, this is a prophecy, and prophecies are not prefaced by “if.” Nonetheless, any prophecy predicting something disastrous need not come true, it is by its very nature a warning, exhorting people to make fulfillment of the prophecy unnecessary. The wording of this paragraph is also what prompted our sages to conclude that Moses in this paragraph alludes to both the destruction of the first Temple, as well as to the destruction of the second Temple. They read this into the wordsונושנתם בארץ, “you will have been in the land for a long time,” and they see in the use of the words בנים ובני בנים a double meaning, as if Moses was exhorting the people to have enough בינה, good sense, to conduct themselves in such a way that what he foresees will not have to become a self-fulfilling prophecy.